As such a link type clamping apparatus, there are conventional ones constructed as follows as described in the following Patent Document 1 (JP2004-74408A).
A rod is vertically movably inserted into a housing, and a female screw hole is opened on an upper surface of an upper wall of the housing at a desired angle position among a plurality of angle positions around the rod. One end portion in a longitudinal direction of a clamp arm is vertically swingably connected to an upper portion of the rod, and an upper portion of a link member is swingably connected to a non-edge portion in the longitudinal direction of the clamp arm. A lower portion of the link member is swingably connected to a head portion of a connect bolt screwed into the female screw hole. Then, by advancing the rod upward, the other end portion of the clamp arm clamps downward an object to be fixed such as a work.    Patent Document 1: Japanese Unexamined Patent Publication 2004-74408